Tractor for installing tubing encapsulated cable into coil tubing

ABSTRACT

Tubing encapsulated cable is generally difficult to place in the interior of coil tubing. In various embodiments of the present invention tubing encapsulated cable is placed in the interior of coil tubing by attaching the tubing encapsulated cable to a tractor and allowing the tractor to pull the tubing encapsulated cable into the coil tubing. The tractor drive system may be a fluid drive system where an electric or other motor supplies power to a propeller or jet pump. The tractor drive system could also be a friction drive were electric or other motor supplies power to a drive wheel or treads. The tractor drive system could also be a push me pull me system where electric or other motor locks a portion of the tractor in place while moving the other portion forwards.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/921,623 that was filed on Dec. 30, 2013.

BACKGROUND

Tubing encapsulated cable can be difficult to insert into coil tubing.Tubing encapsulated cable typically consists of one or more electricalconductors, a fiber optic cable, and possibly other cables or linessheathed in a corrosion resistant alloy such as 316 stainless steel or afiber reinforced composite sheath. The smooth outside surface andrelatively small diameter of tubing encapsulated cable are desirableattributes for well intervention work because the relatively smoothsurface may be more resistant to chemical attack than braided wire.Additionally, the relatively smooth surface and small diameter(0.125″-0.250″) minimizes viscous drag exerted upon the cable as fluidspumped through the coil tubing in the course of intervention operationspass by the cable. Because there is little drag on the tube wire,conventional pumping operations used to install braided wireline intocoil tubing are not sufficient to install tubing encapsulated cable.Pumping fluid through the coil tubing during the installation of tubingencapsulated cable is required to assist in overcoming the capstaneffect, caused by the friction between the coil tubing and the tubingencapsulated cable as the tubing encapsulated cable travels through thewound coil tubing.

There are numerous techniques that may be utilized to install tubingencapsulated cable into a long tubular member such as coil tubing. Suchas hanging the coil into the well in order to allow the somewhatreliable force of gravity to pull the tubing encapsulated cable downwardinto the interior of the coil tubing. Another commonly known techniqueinvolves spooling out the coil tubing along a roadway, installing arope, cable, or equivalent and using the rope or cable in a mannersimilar to that of an electrician's fish tape to pull the tubingencapsulated cable into the coil tubing. In these instances fluid may ormay not be pumped into the coil tubing inserting the tubing encapsulatedcable. Inserting the tubing encapsulated cable into coil tubing asdescribed above can be an expensive operation. Wire and cable have beenused with a tubular conduit since the late 1800s, conduit, like coiltubing, is a long tubular member that normally has wires and cables witha wide variety of outer armors run through it.

SUMMARY

One solution to the problem of running a long tubing encapsulated cableinto coil tubing is to install into the coil tubing a self-propelledassembly that can attach to a tubing encapsulated cable. Theself-propelled assembly could then pull the tubing encapsulated cableinto the coil tubing. In one alternative the self-propelled assembly maypull a first line into the coil where the first line is attached to thetubing encapsulated cable so that the tubing encapsulated cable may thenbe pulled in to the coil tubing by the first line. In anotheralternative the self-propelled assembly may carry the first line or thetubing encapsulated cable on board. As the self-propelled assembly movesthrough the coil tubing the self-propelled assembly may then disburseeither the first line or the tubing encapsulated cable as theself-propelled assembly moves through the coil tubing leaving the firstline or tubing encapsulated cable in place in the coil tubing.

The coil tubing may or may not be coiled around a reel while theself-propelled assembly pulls the tubing encapsulated cable or the firstline into the coil tubing. It may be necessary to pump fluid through thecoil tubing while inserting the tubing encapsulated cable. The fluidtends to provide some lubrication to the interface between the coiltubing and the tubing encapsulated cable. Additionally the turbulentflow of the fluid around the tubing encapsulated cable and also as thefluid flows through the coil tubing tends to cause the tubingencapsulated cable to vibrate reducing the overall friction between thecoil and the tubing encapsulated cable. Also, as the fluid flows pastthe tubing encapsulated cable, the friction between the fluid and thetubing encapsulated cable tends to cause the tubing encapsulated cableto move in the same direction as the fluid thereby helping to push thelength of tubing encapsulated cable. Additionally, it may be preferableto include a tensioning device between the flow tee where the fluid isinjected into the coil tubing and the second reel of the tubingencapsulated cable to prevent the tubing encapsulated cable on thesecond reel from loose wrapping. The net tension in the tubingencapsulated cable between the self-propelled assembly and thetensioning device could be controlled by adjusting either the appliedforce from the self-propelled assembly or the tensioning device.

The tubing encapsulated cable could supply power and/or control signalsto the self-propelled assembly. The self-propelled assembly could useelectrical or hydraulic power supplied through the tubing encapsulatedcable or the self-propelled assembly could utilize internal power suchas batteries or other chemical means of power such as hydrogen peroxidedecomposition or an internal combustion engine. In other embodiments theself-propelled assembly could utilize an electrical generator powered bythe fluid flowing through the coil tubing.

In one embodiment, the self-propelled assembly may use motorized wheelsthat contact the inner surface of the coil tubing, tracks that contactthe inner surface of the coil tubing, or a corkscrew motion wherevarious portions of the self-propelled assembly contact the innersurface of the coil tubing to pull the tubing encapsulated cable intothe coil tubing.

In another embodiment, the self-propelled assembly may consist of ashielded propeller that rotates and creates a pulling force to pull thetubing encapsulated cable into the coil tubing.

In certain instances it may be necessary to pump fluid through the coiltubing as the tubing encapsulated cable is installed into the coiltubing to reduce the capstan effect. Generally the capstan effect iswhere multiple wraps of cable or rope around a cylinder can result in amagnification of friction between the cable or rope and the cylinder. Inthis case the minor diameter of the coil as it is spooled on the drumwould be analogous to the cylinder. The more wraps of rope around thedrum or cylinder result in greater friction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of a tractor powered by a fluid drivesystem puffing a length of tubing encapsulated cable through coiledtubing.

FIG. 2 depicts an embodiment of a tractor powered by a friction drivesystem pulling a length of tubing encapsulated cable through coiledtubing.

FIG. 3 depicts an embodiment of the present invention where the tractorpowered by a push me pull me drive system is in an intermediate state.

FIG. 4 depicts an embodiment of the present invention where the tractorpowered by a push me pull me drive system is in an extended state.

FIG. 5 depicts an embodiment of the present invention where the tractorpowered by a push me pull me drive system is in a retracted state.

DETAILED DESCRIPTION

The description that follows includes exemplary apparatus, methods,techniques, or instruction sequences that embody techniques of theinventive subject matter. However, it is understood that the describedembodiments may be practiced without these specific details.

FIG. 1 depicts an embodiment of the present invention where a tractor 10powered by a fluid drive system 20 is pulling a length of tubingencapsulated cable 30 through fluid-filled coiled tubing 32. In thisinstance the fluid drive system 20 may be a propeller 22 on shaft 24. Inthis particular instance the propeller is configured such that as theshaft 24 is driven in the direction of arrow 26 the propeller 22 willprovide thrust in the direction of arrow 28. While in this embodiment anexternal propeller is shown, the drive system 20 internalized within thehousing 34 could be a jet pump, or any other known system utilizing thefluid as a driving media. Typically the shaft 24 is driven by motor (notshown) that resides about the interior of housing 34. The housing 34 maybe sealed to prevent fluid from entering the housing 34. In certaininstances it may be necessary for the housing 34 to have circumferentialflutes such as flute 40 and 42. The flutes 40 and 42 may serve toprovide additional area to dissipate heat and thus allow for cooling ofthe electric or other motor within the housing 34. Additionally theflutes 40 and 42 may serve as flow passages to allow the relativemovement of fluid past the housing 34 as the housing 34 moves throughfluid in the interior of coil tubing 32. Forward end 44 of housing 32 aswell as rearward end 46 of housing 32 may be angled or have anothershape to minimize drag on the housing 34 as the housing 34 moves throughthe fluid in the interior of coil tubing 32. The tractor 10 may beelectrically, pneumatically, or hydraulically powered. The electricalpower could be provided by internal batteries within the housing 32 orthe power, whether pneumatic, hydraulic, or electric, could be providedthrough the tubing encapsulated cable 30. As shown the tubingencapsulated cable 30 is attached to the rearward end 46 of tractor 10by a compression fitting 50.

FIG. 2 is an alternative embodiment for the tractor 100 utilizing afriction drive system to move the tractor 100 through the fluid-filledcoil tubing 102 while pulling a length of tubing encapsulated cable 120.The housing 122 has a forward end 144 and a rearward end 146. Theforward end 144 and the rearward end 146 of housing 122 may be angled orhave another shape to minimize drag on the housing 122 as the housing122 moves through the fluid in the interior of coil tubing 102. Incertain instances it may be necessary for the housing 122 to havecircumferential flutes such as flute 150. The flute 150 providesadditional area to dissipate heat and thus allow for cooling of theelectric or other motor within the housing 122. Additionally the flute150 may serve as flow passages to allow the relative movement of fluidpast the housing 122 as a housing 122 moves the fluid in the interiorcoil tubing 102. In this embodiment the friction drive system may be atleast one drive wheel 104 and preferably other wheels such as wheels106, 108, 110, 112, and 114 are used to reduce the friction between thehousing 122 and the coil tubing 102. Any one of the wheels or all of thewheels 104, 106, 108, 110, 112, and 114 may be drive wheels. In certaininstances one or all of the wheels may be replaced with tracks. In otherinstances it may be possible to put wheels on one side of the housingand a skid or skids on the opposing side of the housing. In certaininstances the wheels, tracks, or skids may be circumferentially spacedabout the housing. The wheels may be mounted on axles such as axle 124.In certain instances an axle such as axle 126 may be driven by anelectrical or other type motor mounted within housing 122. Power todrive the electrical motor may be supplied by batteries within housing122. In other instances the electrical or other power could be providedthrough the tubing encapsulated cable 130. As shown the tubingencapsulated cable 130 is attached to the rearward end 146 of tractor100 by a compression fitting 150. In addition to supplying theelectrical or other power required to drive the motor within housing 122the tubing encapsulated cable 130 may also supply electrical, optical,or other control signals to the tractor 100. Additionally the tubingencapsulated cable 130 may transmit signals from the tractor 100 to theoperator. Such signals could include a strain gauge to sense pressure onthe tubing encapsulated cable 130 at the tractor 100 allowing theoperator to apply more or less motive force as desired. Other signalsmay include pressure, temperature, tension on the tubing encapsulatedcable 130, or motive power being produced by the tractor 100.

FIG. 3 depicts an embodiment of the present invention where the tractor200 using a push me pull me drive system is in an intermediate statewhere neither the forward slips 210 and 212 nor the trailing slips 214and 216 are in a fully extended position. In this intermediate state thetractor 200 may be inserted into the interior of coil tubing 202.Generally the push me pull me system has an electric or other motorpowering a system to lock a portion of the tractor in place while movingthe other portion forwards.

The tractor 200 has a main beam 220 with the leading end 230 and atrailing end 250. The main beam 220 is configured such that duringoperation of the tractor the distance between the leading end 230 andthe trailing end 250 may be variable.

Towards the forward end of mainbeam 220 is forward pivot point 228attached to forward pushrods 270 and 272 and mainbeam 220. Mounted onforward pushrod 270 at the opposite end from forward pivot point 228 isslip 210. Mounted on forward pushrod 272 at the opposite end fromforward pivot point 228 is slip 212. Forward pushrods 270 and 272 areconnected at pivot point 228 and together form forward interior angle232. A forward bias device 236, such as a torsion spring, is attached toboth forward pushrods 270 and 272 centered about pivot point 228. Theforward pivot point 228 is arranged to allow the distance 224 betweenthe slips 210 and 212 to vary as disk 226 rotates about forward pivotpoint 228. Disk 226 is attached to the mainbeam 220 and forward pivotpoint 228 at forward pivot point 228. A motor 231 on mainbeam 220 drivesthe disk 226 and is connected to disk 226 by a driveshaft and gearbox(not shown). In certain instances the motor 231, driveshaft, and gearboxcould be replaced with hydraulic or pneumatic cylinders. As the cylinderstrokes out the forward slip pivot point 228 would move forward and whenthe cylinder strokes in the trailing pivot point 256 would move forward.The forward bias device 236 is arranged to maximize angle 232 in orderto maintain forward slips 210 and 212 at their maximum distance 224 fromeach other. Any bias device utilized in this invention are typicallysprings but may include a gas cylinder, elastomeric disk, or any otherbiasing device known in the industry.

Towards the trailing end of mainbeam 220 is a trailing pivot point 256attached to trailing pushrods 274 and 276 and to mainbeam 220. Mountedon trailing pushrod 274 at the opposite end from trailing pivot point256 is slip 216. Mounted on trailing pushrod 276 at the opposite endfrom forward pivot point 256 is slip 214. Trailing pushrods 274 and 276are connected at trailing pivot point 256 and together form forwardinterior angle 264. A trailing bias device 262 is attached to bothtrailing pushrods 274 and 276 centered about pivot point 256. Thetrailing pivot point 256 is arranged to allow the distance 278 betweenthe slips 214 and 216 to vary. While the trailing bias device 262, alsoa torsion spring, is arranged to maximize angle 264 in order to maintaintrailing slips 214 and slip 216 at their maximum distance 278 from eachother. Disk 226 is connected to trailing pushrods 274 and 276 attrailing pivot point 256 through rod 258. Rod 258 is attached to disk226 at pivot point 241.

The tractor 200 may be electrically powered. The electrical power couldbe provided by internal batteries mounted on mainbeam 220 or theelectrical power could be provided through conductors within the tubingencapsulated cable 280. As shown the tubing encapsulated cable 280 isattached to the trailing end 250 of tractor 200 by a compression fitting282.

FIG. 4 depicts the tractor 200 in its extended condition as it movesthrough coil tubing 202. In the extended condition motor 231 has causeddisk 226 to rotate such that pivot point 241 is in its most rearwardposition. With the pivot point 241 in its most rearward position thedistance 233 between forward slip 210 and trailing slip 216 ismaximized. Additionally as disk 226 rotates to move pivot point 241 toits most rearward position rod 258 is pushed rearward by moving pivotpoint 256 rearward. Slips 214 and 216 are pushed outward against theinterior of the coil tubing 202. Each of the slips 210, 212, 214, and216 are configured to reduce the amount of force required for forwardmotion and increase the amount of force required for rearward motion.Such slips for example may include but are not limited to cast-ironslips, carbide slips, and wire or other types of stiff brushes. As pivotpoint 256 moves rearward each of the rearward slips 214 and 216 are incontact with the coil tubing walls and as the pivot point 256 movesrearward the rearward slips 214 and 216 tend to dig into the casing tofurther resist backward motion. Once pivot point 256 moves as farrearward as it is capable due to the rearward slips 214 and 216 digginginto the casing, the disk 226 that is attached to pivot point 228 isforced to move forward thereby lengthening beam 220.

FIG. 5 depicts the tractor 200 in its retracted condition as it movesthrough coil tubing 202. In the retracted condition, motor 231 hascaused disk 226 to rotate such that pivot point 241 is in its mostforward position. With the pivot point 241 in its most forward positionthe distance 233 between forward slip 210 and trailing slip 216 isminimized. As disk 226 rotates to move pivot point 241 to its mostforward position rod 258 is pulled forwards while moving pivot point 256forwards. Slips 214 and 216 are pulled inwards from the interior of thecoil tubing 202 thus unlocking the rear of the tractor from the coiltubing and allowing the rear of the tractor to move forward. As pivotpoint 241 moves forward each of the forward slips 210 and 212 are incontact with the coil tubing walls and as the pivot point 241 continuesto move forward the forward slips 210 and 212 tend to dig into thecasing to further resist backward motion. Once pivot point 241 moves asfar forward as it is capable the rear pivot point 256 that is attachedto the disk 226 via rod 258 is forced to move forward thereby shorteningbeam 220 due to the forward slips 210 and 212 digging into the casingpreventing the disk 226 from moving backwards.

While the embodiments are described with reference to variousimplementations and exploitations, it will be understood that theseembodiments are illustrative and that the scope of the inventive subjectmatter is not limited to them. Many variations, modifications, additionsand improvements are possible.

Plural instances may be provided for components, operations orstructures described herein as a single instance. In general, structuresand functionality presented as separate components in the exemplaryconfigurations may be implemented as a combined structure or component.Similarly, structures and functionality presented as a single componentmay be implemented as separate components. These and other variations,modifications, additions, and improvements may fall within the scope ofthe inventive subject matter.

What is claimed is:
 1. A tractor to install a tubing encapsulated cablein coil tubing comprising: a housing, a power source, a connection tothe tubing encapsulated cable, and a friction driver.
 2. The tractor ofclaim 1 wherein, the housing is sealed to prevent a fluid from enteringthe housing.
 3. The tractor of claim 1 wherein, the housing haslengthwise grooves.
 4. The tractor of claim 3 wherein, the lengthwisegrooves allow fluid to pass the housing.
 5. The tractor of claim 3wherein, the lengthwise grooves assist in dissipating heat.
 6. Thetractor of claim 1 wherein, the power source is in the interior housing.7. The tractor of claim 1 wherein, the power source is outside of thecoil tubing and is accessed through the tubing encapsulated cable. 8.The tractor of claim 1 wherein, the friction driver is a wheel.
 9. Thetractor of claim 1 wherein, the friction driver is a track.
 10. Thetractor of claim 1 further comprising a sensor.
 11. The tractor of claim10 wherein, the sensor is a strain gauge.
 12. A tractor to install atubing encapsulated cable in coil tubing comprising: a housing, a powersource, a connection to the tubing encapsulated cable, and a fluiddriver.
 13. The tractor of claim 12 wherein, the housing is sealed toprevent a fluid from entering the housing.
 14. The tractor of claim 12wherein, the housing has lengthwise grooves.
 15. The tractor of claim 14wherein, the lengthwise grooves allow fluid to pass the housing.
 16. Thetractor of claim 14 wherein, the lengthwise grooves assist indissipating heat.
 17. The tractor of claim 12 wherein, the power sourceis in the interior housing.
 18. The tractor of claim 12 wherein, thepower source is outside of the coil tubing and is accessed through thetubing encapsulated cable.
 19. The tractor of claim 12 wherein, thefluid driver is a propeller.
 20. The tractor of claim 12 wherein, thefluid driver is a pump.
 21. The tractor of claim 12 further comprising asensor.
 22. The tractor of claim 21 wherein, the sensor is a straingauge.
 23. A tractor to install a tubing encapsulated cable in coiltubing comprising: a frame, a power source, a connection to the tubingencapsulated cable, and a driver moving the first portion forwards andthen a second portion forwards.
 24. The tractor of claim 23 wherein, thepower source is on the frame.
 25. The tractor of claim 23 wherein, thepower source is outside of the coil tubing and is accessed through thetubing encapsulated cable.
 26. The tractor of claim 23 wherein, thefirst portion engages the coil tubing while the second portion movesforward.
 27. The tractor of claim 23 wherein, the second portion engagesthe coil tubing while the first portion moves forward.
 28. The tractorof claim 23 wherein, the first portion engages the coil tubing withslips.
 29. The tractor of claim 23 wherein, the first portion engagesthe coil tubing with brushes.
 30. The tractor of claim 23 furthercomprising a sensor.
 31. The tractor of claim 30 wherein, the sensor isa strain gauge.